OPTICAL-PROPERTIES OF INXGA1-XN ALLOYS GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

We present the results of optical studies of the properties of InxGa1- xN epitaxial layers (0<x<0.2) grown by metalorganic chemical vapor dep osition. The effects of alloying on the fundamental band gap of InxGa1 -xN were investigated using a variety of spectroscopic techniques. The fundamental band-gap energies of the InxGa1-xN alloys were determined using photomodulation spectroscopy measurements and the variation of the fundamental band gap was measured as a function of temperature. Th e effects of pressure on the band gap for InxGa1-xN samples with diffe rent alloy concentrations were examined by studying the shift of photo luminescence (PL) emission lines using the diamond-anvil pressure-cell technique. The results show that PL originates from effective-mass co nduction-band states. Anomalous temperature dependence of the PL peak shift and linewidth as well as the Stokes shift between photoreflectan ce and PL lines is explained by composition fluctuations in as-grown I nGaN alloys. (C) 1998 American Institute of Physics. [S0021-8979(98)09 520-6].